The present invention relates to modular building construction systems and, more particularly, to prefabricated room modules which may be used to construct room units, optionally including bathrooms or kitchens, for such construction systems, and which may be used, for example, in the construction of dormitory and hotel type accommodation, apartments, social housing and educational buildings.
Room modules for modular building construction systems are conventionally manufactured and prefinished in a factory before being transported to and assembled on site. An advantage of using room modules instead of other traditional building methods is that much of the work is carried out in a factory where labour costs are cheaper. Also, work carried out in a factory is unaffected by adverse weather conditions, unlike work carried out on site.
Bath and shower rooms including toilet facilities, as well as kitchens, may either be installed in the room modules at the construction site in the traditional manner or in a factory, off site. They may be prefabricated in the form of three dimensional components commonly known as xe2x80x9cpodsxe2x80x9d. Hitherto, pods have been transported to the construction site and hoisted into position in the modules in which they are to be installed.
In order for a modular building construction system to be economically viable, it is important to maintain transportation and cranage costs for the room modules, as well as the fabrication costs, at a minimum. In order to maintain such costs at a minimum, the room modules are subject to certain constraints with regard to dimensions and weights. Hence, the maximum width which can presently be transported economically is 3.5 m in certain countries. The maximum load permitted per vehicle is presently 26 tonnes. Consequently, if a room module including a fitted bathroom or kitchen exceeds about 13 tonnes in weight, only one module can be transported at a time, thereby virtually doubling transportation costs. Moreover, the weights of room modules have a direct bearing on cranage costs at a construction site. Modules weighing less than 8 tonnes can be hoisted by a variety of cranes which are relatively cheap to hire, whereas modules weighing 13 tonnes or more need to be hoisted on rather more expensive, specialised cranes. As to fabrication costs, whilst precast concrete of thinner cross section uses less concrete and also weighs less, the cost of such concrete tends to be more per cubic meter because of the increased labour costs involved. Much greater care requires to be taken in making and handling thin concrete components.
Multi-storey buildings erected using a modular construction system typically comprise a plurality of room units assembled from precast concrete modules positioned side-by-side and stacked one on top of another. Such systems are described in U.S. Pat. Nos. 4,050,215 and 4,194,339. Both these systems utilize (a) a series of rectangular room modules, each of which has only two load bearing walls joined by a floor panel and are open at ceiling level, and (b) a series of rectangular tubular room modules, each of which has two opposite load bearing walls for transmitting vertical loads joined via floor and ceiling panels. The (b) modules are used only on the top storey of a building construction, and the (a) modules are used for all the lower storeys. The modules in successive storeys are arranged so that the walls for transmitting vertical loads above are aligned with those below. In the system of U.S. Pat. No. 4,050,215, the room modules on each level are installed with conjugation of the location of the load bearing walls i.e. so that the load bearing walls of any one module in one storey lie perpendicular to the load bearing walls of all immediately adjacent modules in the same storey. In the system of U.S. Pat. No. 4,194,339, the modules in each storey are installed end-to-end so as to form a continuous living space in a longitudinal direction and side-by-side so as to form a separate series of living spaces with double party walls separating the living spaces in the transverse direction.
A problem with precast concrete frame and/or panel construction systems is that if a load bearing wall or column fails, it can cause the progressive collapse of the entire structure above it. Another problem is that these room modules are formed in expensive moulds which are required for casting the opposed walls so as to be mutually parallel. Additionally, the moulds may also be required to form mutually parallel floor and ceiling panels.
It is an objecT of the present invention to alleviate the above problems and provide a room module having a more stable modular construction.
According to one aspect of the present invention there is provided a prefabricated room module for use in the construction of a modular building, comprising a slab of generally rectangular shape in plan, and load bearing walls, characterized in that the slab is a floor or ceiling slab and that said load bearing walls are formed at adjacent sides of the slab and mutually adjoin at a common corner.
The room module of the invention may be of monolithic precast and reinforced concrete construction. Such a module integrally formed from precast concrete is inherently much stronger than other known room modules and enables a reduction in the use of materials and waste.
It may be desirable for one of the walls of the room module to be prefabricated with at least one door or window opening and this wall, in the modular building, may form an outside wall or corridor wall section, depending on the type of opening, with the other load bearing wall forming a party wall.
Conveniently, the room module can include a prefabricated bathroom or kitchen pod.
A module according to the invention and, preferably, cast with a floor slab, is suitable for use in erecting low cost accommodation, such as, dormitories and two star hotels. A suitable room unit for such accommodation may be provided by a room module which is approximately 6 mxc3x973 m. The load bearing wall along the shorter side of the floor slab is cast with a window opening and forms the inner skin of an outer cladding system of the building. The other load bearing wall is a party wall. Such modules may be stacked one on top of the other up to a height of 10 storeys with the same load bearing wall thickness for all storeys. For example, up to 10 storeys the load bearing walls will generally be of the order of 100 mm thick unless for acoustic purposes they need to be made up to 150 mm thickness. Floors up to 3.2 m spans may be of the order of 100 mm thick and longer spans, up to xc2x14 m, will be 120 mm thick. If greater acoustic properties are required for floors, a floating floor may be provided on top of the floor slab. The modules are stacked with the load bearing walls of the modules aligned in vertical planes.
Conveniently, a third wall of less width than the module is cast along the corridor side of the floor slab, opposite the wall having the window opening, and in adjoining relation with the adjacent party wall, whereby a bathroom pod may be accommodated between this third wall, which forms a corridor wall, and the party wall. Such a module affords constructors an added advantage in that the bathroom pods can be delivered to the factory in which the modules are precast and where they can be installed in the module prior to delivery to the construction site. This has a number of advantages, the main one being the saving of time at the site as the pod is hoisted into position as part of the module and not as a separate element. The maximum weight of this module, including the bathroom pod, is advantageously less than 13 tonnes.
Fixing points for mechanical fastening devices may be cast into the floor or ceiling slab and load bearing walls at or adjacent their free edges so as to enable the module to be tied to adjacent modules both horizontally and vertically. At least the free edge of the floor or ceiling slab opposite the load bearing wall serving as a party wall may be cast with projecting tongues and the opposite edge of the slab, below the party wall, may be cast with complementary rebates, whereby the projecting tongues can rest in the rebates of an adjacent similar module in the same storey and be supported by the load bearing wall of another similar module in the storey below.
Where a building construction requires longer or larger room units which cannot be constructed from a single room module according to the invention without breaching the above mentioned constraints, the room unit may be assembled from a main room module constructed according to the invention and one or more prefabricated supplementary modules, each of which comprises a rectangular floor or ceiling slab and a load bearing wall along one side of the slab so as to coincide with the party wall of the main module. The supplementary module is adapted to be fixed to the main module with the free sides of its slab and load bearing wall contiguous with the free sides of the slab and party wall of the main module.
In one embodiment suitable, for example, for constructing three star hotels, the room unit may be assembled from one main module comprising two adjacent load bearing walls and a floor slab, and one supplementary module. The supplementary module may be fitted with a bathroom or kitchen pod. In those cases where the constructor requires the floor level of a bathroom to be the same as the bedroom lobby, the supplementary module may be set down slightly to permit this to be achieved. The resulting recess may then be filled with lightweight screed. Alternatively, the whole floor of the room unit may be raised with a floating floor or screed to match the floor level of the bathroom or kitchen pod.
In another embodiment having larger room units, such as may be required, for example, for four star hotels, the room unit may be formed from a main room module and two supplementary modules to permit economic transportation. Such room units may have a clear internal width exceeding 3.2 m. For four star hotels, the overall dimensions of a room unit comprising the three modules may be about 3.7 mxc3x976.5 m and for five star hotels 4 mxc3x978 m. A prefabricated bathroom pod may be installed in the outer one of the supplementary modules which will be adjacent the corridor of a hotel.
In embodiments utilising supplementary modules, the room units can also be stacked up to a height of ten storeys utilising the same wall thickness for all storeys. The maximum weight of the heaviest of the modules should be less than 8 tonnes, thus reducing the cost of cranes needed for hoisting purposes. In these embodiments, the floor slab of the or each supplementary module will span across the width of the room unit and, similarly to a main room module constructed according to the invention, each supplementary module may be cast with tongues projecting from the edge of the slab opposite the load bearing wall and with complementary rebates in the corner edge between the slab and the wall so that the tongues of the floor slab can bear on the party wall of a like supplementary module in the storey below.
According to another aspect of the present invention there is provided a prefabricated room module for use in the construction of a multi-storey modular building, comprising a floor or ceiling slab, a wall formed along one side of the slab, at least one upright projection from a top or bottom edge of the wall, at least one first anchor member at the opposite edge of the wall having a first coupling hole for engaging a cooperating projection of an adjoining like module in the next storey above or below, at least one second anchor member projecting from the edge of the slab opposite the wall and having a second coupling hole also for engaging a cooperating projection of an adjoining like module in the next storey above or below, and means for securing the projection through cooperating first and second holes of adjoining like modules.
When the room module has a floor slab, the projection(s) are conveniently on the top edge of the wall and, when the room module has a ceiling slab, the projection(s) are conveniently at the bottom edge of the wall.
When erecting a building using, for example, room modules embodying the invention and comprising floor slabs, the room modules in an upper storey are lowered onto the modules of the storey immediately below and are assembled so that the projection(s) from the wall of a room module in the storey below engage the coupling holes in the anchor members of the two room modules in the upper storey having, respectively, the free edge of its floor slab and the bottom edge of its wall supported on the upper edge of the wall of the lower module wall. The projection(s) are then secured to the anchor members so as to tie the three adjoining modules together in both the horizontal and vertical directions. Preferably, the projection(s) are bolts or other screw threaded rods which are secured to the anchor members by nuts.
The invention also consists in a modular building construction system erected using prefabricated room modules according to the invention.
Embodiments of the present invention will now be described by way of example with reference to the accompanying drawings.